writef, compile-checked format, pointer

[Adam D Ruppe]

On Monday, 9 August 2021 at 22:30:43 UTC, Ali Çehreli wrote:
> I don't know the reason but I suspect a bug in the compile-time 
> checker that involves .init values for arguments.

The compile time checker is pretty bad tbh, it just tries to ctfe 
execute the given string and sees if it throws. That's kinda 
clever; the simplest thing that can possibly work, no doubt. But 
since ctfe cannot work with certain things - like the pointer 
casts which are done here* - this makes it a bit fragile. And the 
implementation is really really slow and pretty bloated in 
codegen too.

My personal policy is to never use it.

* The compiler probably could special-case `null` at least since 
that's consistently 0 in D.

> Perhaps the un-typed 'null' literal is used somewhere.

The line is this:

const pnum = () @trusted { return cast(ulong) p; }();


Which is already blargh code, but in ctfe it is a prohibited 
operation.